1. Field of the Invention
The present invention relates to an insulating joint for use in a rail system to electrically isolate parts of the rail system from each other.
2. Description of the Prior Art
A rail system is generally divided into sections or blocks to be able to detect trains which permits more trains to travel on one stretch of track or rail. Each section is electrically isolated from all other sections so that when no train is present in the section, a high electrical resistance can be measured over the parallel railbars in the section. When a train enters a section, the train short circuits adjacent railbars and the electrical resistance drops.
Railbars are generally welded to each other or attached to each other by a steel joint. High performance non-metallic joints are used for electrically isolating two railbars in order to build an electrically isolated section. Switches are insulated in the same way by dividing both gauge plate and switch rods into two parts and by joining the respective parts with a non-metallic joint.
Known non-metallic joints are very expensive because of the special high performance material which has to endure high tensile and flexural forces. One such non-metallic material used for the joints is a laminated SCOTCHPLY(copyright) material manufactured by 3M of St. Paul, Minn. In addition, a separate insulating plug must be utilized between ends of the gauge plate or switch rod to prevent material buildup of debris which would then cause an electrical short.
An object of the present invention is to provide an insulating joint whereby the above drawbacks are eliminated.
According to the present invention, an insulating joint is provided, including a metallic core body having at least one hole formed in the body and a first insulating layer covering the outer surface of the body. A second insulating layer can be arranged in the holes. Preferably, the insulating layer is made of polyurethane. Alternatively, a rubber layer can be used.
An advantage of the present invention is that it is less expensive to manufacture than the prior art SCOTCHPLY(copyright) arrangements.
A preferred embodiment of the present invention further includes bushings in the holes to account for pressure forces exerted by the bolts used for joining, for example, two switch rods or gauge rods.
Preferably, a second insulating layer is arranged on an outer surface of the bushing. This will enable the simple exchange of new bushings when the bushing or the second insulating layer becomes worn.
Preferably, the insulating joint is T-shaped, wherein the core is likewise T-shaped. The core includes a flat base and a ridge or leg depending from the base. The T-shaped core is covered with the insulating layer.
Further, the present invention is an electrically insulated rail member to be secured to rails having an electric current passing through the rails that includes a metallic core and an electrically insulating material encasing the metallic core. The metallic core can be flat or T-shaped. Further, the metallic core can be made of steel. The electrically insulating material can be molded about the metallic core. The T-shaped cross section is defined by a flat body and a depending leg. The metallic core can be flat and the depending leg can be completely defined by the electrically insulating material. The present invention can be used as a switch plate or a gauge plate.
The metallic core encased with the electrically insulating material defines a body having a hole adapted to receive a fastener for securing the electrically insulated rail member to an adjacent metallic member for maintaining a gauge of two adjacent rails, wherein the fasteners are electrically insulated from the metallic core. A plurality of holes can be defined in the body for receiving fasteners for maintaining a gauge of two adjacent rails, wherein the fasteners are electrically insulated from the metallic core.
The present invention is an arrangement for maintaining the gauge between a first rail and a second rail to form a track having a current passing therethrough and includes a first member extending from the first rail toward the second rail, a second member extending from the second rail toward the first rail and a gauge plate secured to the first member and the second member. The gauge plate includes a metallic core and an electrically insulating material encasing the metallic core whereby the electrically insulating material electrically insulates the first member from the second member. The arrangement includes a gap defined between the first member and the second member, wherein the gauge plate further includes a body having a leg depending therefrom, wherein the leg is received within the gap.
The present invention is also an arrangement for coupling a first rail and a second rail to form a track having an electric current passing therethrough and includes a first member extending from the first rail toward the second rail and a second member extending from the second rail toward the first rail. A first plate is secured to the first member and the second member and includes a metallic core and an electrically insulating material encasing the metallic core. A second plate is provided having an electrically insulating material encasing a metallic core. The first plate and the second plate sandwich ends of the first member and the second member which are secured thereto. The first plate and the second plate can be T-shaped having legs depending therefrom which are received within a gap defined by the first member and the second member. The legs can abut against each other. Holes are defined in the first plate and the second plate that align with holes defined in the first member and the second member, respectively, and fasteners pass through the respective holes. The holes can be defined by bushings received by the plates.
The present invention is also a method for manufacturing a T-shaped electrically insulating plate for use in coupling two rails having electric current passing therethrough, comprising the steps of: providing a metallic core; and encasing the metallic core with an electrically insulating material and forming a T-shaped electrically insulating plate. The method can further include providing bushings in the plate for receipt of fasteners.